Specification
=============

SDN Features
------------
  - ONOS cluster of all-active N instances affording N-way redundancy and scale, where N = 3 or N = 5
  - Unified operations interface (GUI/REST/CLI)
  - Centralized configuration: all configuration is done on the controller instead of each individual switch
  - Centralized role-based access control (RBAC)
  - Automatic host (end-point) discovery: attached hosts, access-devices, appliances (PNFs), routers, etc.
    based on ARP, DHCP, NDP, etc.
  - Automatic switch, link and topology discovery and maintenance (keepalives, failure recovery)

L2 Features
-----------
Various L2 connectivity and tunneling support

  - VLAN-based bridging

    - Access, Trunk and Native VLAN support
  - VLAN cross connect

    - Forward traffic based on outer VLAN id
    - Forward traffic based on outer and inner VLAN id (QinQ)
  - Pseudowire

    - L2 tunneling across the L3 fabric
    - Support tunneling based on double tagged and single tagged traffic

      - Support VLAN translation of outer tag

L3 Features
-----------
IP connectivity

  - IPv4 and IPv6 unicast routing (internal use of MPLS Segment Routing)
  - Subnetting configuration on all non-spine facing leaf ports; no configuration required on any spine port
  - IPv6 router advertisement
  - ARP, NDP, IGMP handling
  - Number of flows in spines greatly simplified by MPLS Segment Routing
  - Further reduction of per-leaf flows with route optimization logic

DHCP Relay
----------
DHCP L3 relay

  - DHCPv4 and DHCPv6
  - DHCP server either directly attached to fabric leaves, or indirectly connected via upstream router
  - DHCP client directly either attached to fabric leaves, or indirectly connected via LDRA
  - Multiple DHCP servers for HA

vRouter
-------
vRouter presents the entire SD-Fabric as a single router (or dual-routers for HA),
with disaggregated control/data plane

  - Uses open-source protocol implementations like Quagga (or FRR)
  - BGPv4 and BGPv6
  - Static routes
  - Route blackholing
  - ACLs based on port, L2, L3 and L4 headers

Multicast
---------
Centralized multicast tree computation, programming and management

  - Support both IPv4 and IPv6 multicast
  - Dual-homed multicast sinks for HA
  - Multiple multicast sources for HA

API
---
- Provide easy access for 3rd party edge application developers and for the Aether centralized management platform
- Support for traffic redirecting, dropping, network slicing and QoS

Programmability
---------------
- Support for Stratum, P4Runtime and gNMI and P4 programs
- Innovative services enabled by programmable pipeline
  - 4G/5G UPF - GTP encap/decap, idle-mode buffering, QoS and more
  - BNG - PPPoE, anti-spoofing, accounting and more

Troubleshooting & Diagnostics
-----------------------------
- T3: Troubleshooting tool to diagnose broken forwarding paths fabric wide
- ONOS-diags: One-click Diagnostics collection tool

.. _Topology:

Topology
--------
SD-Fabric can start at the smallest scale (single leaf) and grow horizontally.

.. image:: images/topology-scale.png
  :width: 900px


Single Leaf (ToR)
^^^^^^^^^^^^^^^^^
This is the minimum SD-Fabric setup. In this setup, all servers are connected to a single switch.

.. image:: images/topology-single.png
  :width: 160px

Single Leaf Pair (Dual-Homing)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Compared to single switch, it provides more redundancy in terms of server NIC failure and link failure.

.. image:: images/topology-pair.png
  :width: 225px

Leaf-Spine (without pairing)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Compared to single switch, it offers more redundancy in terms of switch failure and provides better scalability.

.. image:: images/topology-2x2.png
  :width: 300px

Leaf-Spine (with pairing)
^^^^^^^^^^^^^^^^^^^^^^^^^
It supports all the redundancy and scalability features mentioned above.

.. image:: images/topology-2x4.png
  :width: 450px

Multi-Stage Leaf-Spine
^^^^^^^^^^^^^^^^^^^^^^
Multi-stage is specifically designed for telco service providers.
The first stage can be installed in the central office, while the second stage
can be installed in a field office that is closer to the subscribers.
Two stages are typically connected via long distance optical transport.

.. image:: images/topology-full.png
  :width: 700px

Resiliency
----------
Provides HA in following scenarios

  - Controller instance failure (requires 3 or 5 node ONOS cluster)
  - Link failures
  - Spine failure

Further HA support in following failure scenarios with dual-homing enabled

  - Leaf failure
  - Upstream router failure
  - Host NIC failure

Scalability
-----------
In Production

  - Up to 80k routes (with route optimization)
  - 170k Flows
  - 600 direct-attached hosts
  - 8 leaf switches
  - 2 spine switches

In Pre-Production

  - Up to 120k routes (with route optimization)
  - 250k flows
  - 600 direct-attached hosts
  - 8 leaf switches
  - 2 spine switches
  - 5000 active UEs, 10 call per second

Security
--------
  - TLS-secured connection between controllers and switches (premium feature)
  - AAA 802.1x authentication

Aether-ready
------------
Fully integrated with Aether (5G/LTE private enterprise edge cloud solution)
including deployment automation, CI/CD, logging, monitoring, and alerting.

Overlay Support
---------------
Can be used/integrated with 3rd party overlay networks (e.g., OpenStack Neutron, Kubernetes CNI).

Orchestrator Support
--------------------
Can be integrated with an external orchestrator, optionally running from the public cloud
Supports logging, telemetry, monitoring and alarm services via
REST APIs and Elastic/Fluentbit/Kibana, Prometheus/Grafana

Controller Server Specs
-----------------------
Recommendation (per ONOS instance) based on 50K routes

  - CPU: 32 Cores
  - RAM: 128GB RAM. 64GB dedicated to ONOS JVM heap

White Box Switch Hardware
-------------------------
- Multi-vendor: APS Networks™, Dell™, Delta Networks™, Edgecore Networks™, Inventec™, Netburg™, QCT™
- Multi-chipset:
  - Intel Tofino (supports all features, including programmability, UPF & INT)
  - Broadcom Tomahawk®, Tomahawk+®, Trident2 (traditional fabric features only)
- 1/10G, 25G, 40G, 100G
- Refer to Supported Devices list in https://github.com/stratum/stratum for the most up-to-date hardware list

White Box Switch Software
-------------------------
- Open source ONL, ONIE, Docker, Kubernetes
- Stratum available from ONF